Identification of Microorganisms

Species – Genus – Group

It is desirable to identify isolated microorganisms form raw materials and finished products as well as from the environment. We identify microorganisms to different levels depending on what type of information that is needed. Grouping of microorganisms give you information about possible sources for the contamination. It can also be of great value to know if the contaminant is a sporulating organism, which can be more difficult to eliminate. Also, when growth over limit is detected it can be a requirement from authorities to know the exact identity of the microorganism, primarily for risk assessment but also to facilitate tracing the source of contamination.

Species determination of microorganisms

Complete identification of microorganisms, down to species level, is performed using VITEK MS.

VITEK MS is based on the innovative MALDI-TOF technology. The test requires minimum preparation as a bacterial-, yeast- or mould colony is placed on a sample slide and analysed directly in the instrument.Inside the instrument, the sample is ionized and the protein pattern of the sample generates a spectrum which is then compared against a comprehensive database of microorganisms. The analyse takes between 45 – 90 seconds.

Normally, complete identification is done for growth in grade A and growth over limits for products, raw materials, water or grade B environmental control samples when the problems are recurring (deviation investigation).

Identification of mould to genus level

Identification of mould is performed using MALDI-TOF, macroscopic- and microscopic examination.

Gram staining of bacteria and yeast

By performing a gram stain it is possible to identify the organism as gram positive or gram negative rod or cocci, alternatively as yeast. A gram stain can also determine what other tests that may be needed in order to definitely identify the microorganism.

Grouping of microorganisms

A microorganism can be divided into different groups by performing additional tests after a gram stain. The different groups of microorganisms are:

Gram positive cocci, (ex S. aureus or Streptococcus spp

Gram positive cocci, probably S. aureus

Gram positive cocci, probably Streptococcus spp

Gram negative cocci

Gram positive rod, non-sporulating

Bacillus spp (sporulating rods)

Gram negative rod, fermenting

Gram negative rod, non-fermenting

Yeast

Analysis result, lead time

Given that your samples are sent as fresh bacterial colonies (< 1 day) on an agar plate, the normal time requirement from customer order to analysis report-out is 6 days. Unless stated, we need to re-grow the microorganisms on fresh growth media, resulting in a total analysis response time of 7 days for bacteria and 9 days for mold. Samples received on Fridays after 14:00 will be analyzed next working day. For more information, see general terms and conditions.